Convert //ash from scoped_ptr to std::unique_ptr

ash/accelerators/key_hold_detector.h

Index: ash/accelerators/key_hold_detector.h
diff --git a/ash/accelerators/key_hold_detector.h b/ash/accelerators/key_hold_detector.h
index f50a35cb61994c84211065678443234874ad42f2..af03cb20e8ecf6fed00f687f9c30427ddab53889 100644
--- a/ash/accelerators/key_hold_detector.h
+++ b/ash/accelerators/key_hold_detector.h
@@ -5,9 +5,10 @@
 #ifndef ASH_ACCELERATOR_KEY_HOLD_DETECTOR_H_
 #define ASH_ACCELERATOR_KEY_HOLD_DETECTOR_H_
 
+#include <memory>
+
 #include "ash/ash_export.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 #include "ui/events/event_handler.h"
 
 namespace ui {
@@ -42,7 +43,7 @@ class ASH_EXPORT KeyHoldDetector : public ui::EventHandler {
     virtual void OnKeyUnhold(const ui::KeyEvent* event) = 0;
   };
 
-  explicit KeyHoldDetector(scoped_ptr<Delegate> delegate);
+  explicit KeyHoldDetector(std::unique_ptr<Delegate> delegate);
   ~KeyHoldDetector() override;
 
   // ui::EventHandler overrides:
@@ -65,7 +66,7 @@ class ASH_EXPORT KeyHoldDetector : public ui::EventHandler {
   };
 
   State state_;
-  scoped_ptr<Delegate> delegate_;
+  std::unique_ptr<Delegate> delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(KeyHoldDetector);
 };